Blast Furnace

The Blast Furnace is a 3x3x4 multiblock structure used to convert Iron into Steel, smelt aluminum dust, and salvage metal from some items, among other things. The oven is built out of 34 Blast Furnace Bricks constructed in a 3 wide, 3 deep, 4 high box:

Base and top layers: 3x3

Middle two layers: 3x3 with hollow center

To produce the 34 Blast Furnace blocks, the following ingredients are required, all of which are found in the Nether.

Two Blast Furnace Bricks will be left over after constructing the furnace. When building a Blast Furnace, you will know it is complete when a window appears in the bottom middle block on the sides. Blast Furnaces cannot be built directly adjacent to each other - there must be a gap of at least one block between them.

The Blast Furnace accepts only two types of fuel: Charcoal or Coal Coke. It will take 1 minute and consumes one piece of Coal Coke or four pieces of Charcoal to convert one Iron Ingot into a Steel Ingot. The same amount applies to aluminum. Each piece of Coal Coke lasts a few seconds longer than it takes to cook an Ingot, such that processing a stack of Iron with a stack of Coal Coke will finish with ~3 pieces of coal left over.

While the Blast Furnace is active, the center will contain lava, which can spill out if the furnace is broken.

The furnace can be loaded and unloaded automatically like other machines. The entire furnace is treated as a single block, similar to a large vanilla chest. It will accept Coal Coke, Charcoal, and Iron from any side and will output Steel only from the right hand side. However with pneumatic tubes, the blast furnace will only accept Coal Coke from the bottom, and if loaded anywhere else it will be placed in the output.